2021/08/23 CAD二次开发程序在自定义UCS运行注意事项

部分转载至此文~感谢作者！

注意事项

1. AutoCAD 界面中，通过手动操作创建的图元都是基于 UCS 的
2. 通过程序点选获取的坐标点是是基于UCS
3. 通过程序程序创建图元都是基于WCS(即自动生成基于WCS)
4. 通过程序解析图元的坐标点都是基于WCS

代码示例

提取CAD地形线(多段线)标高，并以单行文字在原位置标注该标高

// 修改前的代码
        public static void MarkElevation()
        {
            Document acDoc = AcadApp.DocumentManager.MdiActiveDocument;
            Editor acEd = acDoc.Editor;

            PromptEntityOptions pCurveOpt = new PromptEntityOptions("请选择要标注的曲线");
            PromptEntityResult pCurveRes = acEd.GetEntity(pCurveOpt);
            if (pCurveRes.Status == PromptStatus.OK)
            {
                Database acCurDb = acDoc.Database;
                using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
                {
                    Polyline acCurve = acTrans.GetObject(pCurveRes.ObjectId, OpenMode.ForRead) as Polyline;
                    if (acCurve != null)
                    {
                        DBText acText = new DBText();
                        acText.TextString = acCurve.Elevation.ToString();
                        acText.DtRotateToCurve(acCurve, pCurveRes.PickedPoint);
                        acText.Justify = AttachmentPoint.MiddleCenter;
                        acText.AlignmentPoint = acCurve.GetClosestPointTo(pCurveRes.PickedPoint, true);
                        acText.ColorIndex = 2;
                        acText.WidthFactor = 0.7;
                        BlockTable blkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead) as BlockTable;
                        BlockTableRecord blkTblRec = acTrans.GetObject(blkTbl[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
                        blkTblRec.AppendEntity(acText);
                        acTrans.AddNewlyCreatedDBObject(acText, true);
                        acTrans.Commit();
                    }
                }
            }
			
// 修改后的代码
	public static void MarkElevation()
        {
            Document acDoc = AcadApp.DocumentManager.MdiActiveDocument;
            Editor acEd = acDoc.Editor;

            PromptEntityOptions pCurveOpt = new PromptEntityOptions("请选择要标注的曲线");
            PromptEntityResult pCurveRes = acEd.GetEntity(pCurveOpt);
            if (pCurveRes.Status == PromptStatus.OK)
            {
                Database acCurDb = acDoc.Database;
                using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
                {
                    Polyline acCurve = acTrans.GetObject(pCurveRes.ObjectId, OpenMode.ForRead) as Polyline;
                    if (acCurve != null)
                    {
                        Point3d transPoi =pCurveRes.PickedPoint.TransformBy(acEd.CurrentUserCoordinateSystem);//将程序点选坐标转换到Wcs坐标
                        DBText acText = new DBText();
                        acText.TextString = acCurve.Elevation.ToString();
                        acText.DtRotateToCurve(acCurve, transPoi);
                        acText.Justify = AttachmentPoint.MiddleCenter;
                        acText.AlignmentPoint = acCurve.GetClosestPointTo(transPoi, true);
                        acText.ColorIndex = 2;
                        acText.WidthFactor = 0.7;
                        BlockTable blkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead) as BlockTable;
                        BlockTableRecord blkTblRec = acTrans.GetObject(blkTbl[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
                        blkTblRec.AppendEntity(acText);
                        acTrans.AddNewlyCreatedDBObject(acText, true);
                        acTrans.Commit();
                    }
                }
            }